Construction material based on activated mixture of fly ash, slag or other sources of aluminosilicates, including or not cement clinker have been widely described.
The prior art related to these materials did not disclose the workability and workability retention of these materials. In WO2009024829 some flow properties have been given to show that the slump of those construction mixes could range from some centimeters to 25 cm, but no data are reported on the workability retention and the relation to the rheology parameters of the mixes. It could also be seen on WO2009024829 than high values of slump were related to high water/binder ratio, leading to poor early strength development.
Most of the available literature does not demonstrate any of the requirements of industrial applications (effect of large and small aggregates in large quantity, mixing, placing, segregation risk, transportation, etc.). The available literature is relevant from a chemical and reactivity stand point of view; however scaling up from paste tests (binder+activator+water) to real construction material for industrial application is not evident and many systems described as pastes have never been used as construction material due to the difficulty of solving the problems.
One of the known problems of these mixes is that their alkalinity is so high that normal admixture technology (based only on organic polymer like melamine or polycarboxilates-based superplasticizers) cannot be used successfully, and that the stability of the aggregates in the binder (paste) is not ensured leading to important segregation as soon as the slump increases. Segregation is inacceptable for industrial application since it yields heterogeneities and defaults.
Castable construction materials shall be offered in a wide range of workability, including pumpable and self compacting (SCC) mixes and a wide range of final strength from 20 to 80 Mpa. In addition, the really strength shall be high enough to enable the removal of the framework of moulds in less than 2 days.
Finally, the workability retention, (E.g. the capacity of the rheology parameters like flow, viscosity, yield stress, etc.) has to be high enough to encompass dispatching problems related to delay, traffic, etc. so the placing properties on the job site are not affected by logistics issues.
Therefore, the invention proposes a new robust construction material, comprising a binder containing fly ashes, ground granulated blast furnace slag and pozzolanas, an activator and aggregates. Said new construction material has placing properties that ranks from S1 to S5 and flow from F1 to F6 without segregation between aggregates and paste, developing an early strength higher or equal to 2 MPA after 1 day and having workability retention that ranks from 15 minutes to 180 minutes.
More likely, the invention targets to obtain slump from S3 and S5 and/or flow from F4 to F6, having workability retention from 30 minutes to 150 minutes, more likely from 30 minutes to 120 minutes.